The present application relates to recovering and beneficiating particulate additives like weighting agents.
As used herein, the term “particulate additives” refer to solids intentionally added to a wellbore fluid by an operator. Particulate additives typically have particle sizes below about 300 microns and, in some instances, below about 100 microns and, in some instances, below about 5 microns. As used herein, “drill solids” refer to formation solids added to the wellbore fluid as a result of drilling the wellbore, for example, particulates of the rock, clay, or other formation composition being drilled through.
Weighting agents are a common particulate additive added to wellbore fluids to change the specific gravity of the fluid. While drilling a well into a subterranean formation, the wellbore fluid suspends the drill solids, which are the small pieces of formation that break away from the formation due to the drilling. These drill solids have a lower specific gravity than the weighting agents and cause the specific gravity of the fluid to decrease. Therefore, separation techniques are employed to remove drill solids. For example, shale shakers, hydrocyclones, such as desanders and desilters, and centrifuges are used to remove the drill solids in a step-wise manner by removing particles the large particles first and sequentially smaller particles. However, many of the drill solids are about the same size as the particulate additives. Therefore, drill solids often remain in the wellbore fluid after implementing separation methods, which may adversely impact the specific gravity of the wellbore fluid, especially, when the wellbore fluid is reused or recirculated many times in a wellbore operation.
For example, drilling operations use a drilling fluid several times until the drilling fluid is unusable due to significant changes in drilling fluid properties caused by accumulation of fine and colloidal drill solids. At this stage, the drilling fluid is often referred to as a “spent drilling fluid.” In some instances, a portion of the spent drilling fluid may be diluted and then further used. However, a significant portion of the spent drilling fluid is disposed of or processed to reclaim the continuous phase. The solids that remain after such processing are disposed of even though the solids contain significant amounts of reusable particulate additives like barite and calcium carbonate.